Hi,
MGM's & MK parades are really cute and your 20 month old will probably enjoy seeing them. As for Fantasmic, I don't know. I personally think this is the best thing at Disney. Problem is that this show is held in an arena area and has fire works going off at different points throughout the show which last about 30/35 mins). It is truly the greatest thing to see but due to the arena enclosure may get a little bit loud. I was sitting 2 rows in front of a lady who had a child that looked to be about 1 1/2 old and not to long after the show began, the child did begin to cry and she did leave the area for the rest of the show. I think it depends on your child. I would definately tell you to attempt Fantasmic and worst comes to worst, should your child get upset then leave and wait a few years. Another parade that is so great to see is Spectromagic in the MK (electric night parade in the MK). However, it may not parade too often in the off season or if it does it may only be on a Saturday night.
As for Epcot's parade ToD, I really didn't enjoy it. It is hard to describe this parade. It is more of a costume type of parade where CMs have these big puppet type devices attached to them that stand 9/10 feet in the air and are operated mostly with their hands/feet. This paraded at night back in December and I don't recall a lot of younger children at it (mostly 5 and older around me). To tell you the truth, I don't even recall seeing one usual disney character in the parade but could be wrong. Usually Disney had Mickey, Minnie and Goofy in all of their parades but I really don't recall them in this one (excuse my alzheimer moment). The only thing that I did like was the music that went along with the parade. I did find that upbeat and enjoyed it.
If your going to AK, stay for that parade as well. It is sort of a mixture of Epcot's parade meets MK parade but it is enjoyable and beware, the crowd will find their viewing spots early.
